1. Field of the Invention
This invention relates to a sheet feeding device for separating and conveying a sheet (a sheet-shaped substance or a sheet material) typified by paper, a sheet treating device provided with the sheet feeding device, and an image reading apparatus provided with the sheet feeding device.
2. Related Background Art
For the sake of convenience, description will hereinafter be made of an example of an image reading apparatus for reading an image recorded on a sheet-shaped original by a close sensor or the like, and delivering the read image data or recording the read image data on a recording medium.
This image reading apparatus has an original stacking portion stacking originals thereon and moving them to an original introducing position, and this original stacking portion is controlled so as to position the level of the uppermost one of the originals stacked thereon within a predetermined range relative to the original introducing port of the image reading apparatus.
a) The original stacking portion is moved so that the originals may be located at a prescribed level, whereafter the uppermost one of the originals with which a pickup roller is in contact is fed to, or in case that the uppermost original and an original just beneath the uppermost original are carried away by the friction between the originals, a plurality of originals are fed to a sheet separating portion (a contact portion or a nip portion) formed by a feed roller as a forwardly rotating conveying rotary member and a separating roller as a reversely rotating separating rotary member, by the pickup roller.
The sheet separating portion formed by the feed roller and the separating roller has the center distance between the feed roller and the separating roller set to a state in which in the initial state, the passage of any original is not permitted.
b) The change of the center distance by the relative movement of the feed roller and the separating roller is started by a first detection signal from first detecting means for detecting that the leading end of an original has come to just the front of the sheet separating portion.
That is, the feed roller and the separating roller has the center distance therebetween widened relatively by center distance changing means having a motor or the like as a drive source, and when they have come to assume such a positional relation that only the uppermost one of the originals can pass, that original passes through the sheet separating portion.
c) The operation of widening the center distance is stopped by a second detection signal from second detecting means disposed just after the separating portion for detecting that the leading end of the original has passed through the separating portion.
d) When it is detected by the second detecting means that the trailing end of the original has passed through the sheet separating portion, the feed roller and the separating roller are driven so as to restore the center distance therebetween to its initial state.
The apparatus operation described under items a) to d) above is the operation of automatically adjusting the center distance between the feed roller and the separating roller for the separation of a sheet, and this operation cycle is repetitively executed each time an original is fed.
By this center distance automatic adjusting operation method, the sheet separating portion starts the sheet separating and conveying operation from the initial state without fail and therefore, originals of any thickness are conveyed one by one in the apparatus.
After the original has passed through the sheet separating portion, it passes through an image reading portion by a conveying roller, a conveying belt or the like disposed as required, and is discharged from a discharge port.
In an image reading apparatus having a sheet feeding portion having no mechanism for automatically adjusting the center distance between the feed roller and the separating roller for each original as described above, sheet feeding was effected with the center distance between the feed roller and the separating roller manually and mechanically adjusted and fixed in accordance with the size, thickness, paper quality, etc. of the original being conveyed.
Even when in the above-described example of the conventional art, there is provided a sheet feeding device capable of performing the sheet feeding operation while automatically adjusting the center distance between the feed roller and the separating roller for each original, if the size, thickness and paper quality of the originals being conveyed are uniform or can be regarded as being substantially uniform in the bundle of originals, it can omit the operation of operating the relative center distance in the widening direction from the initial state for each original, and narrowing it back to the initial state and the performance of the apparatus may heighten (the number of originals treated per unit time is increased by the sheet-to-sheet distance being shortened) if the sheet feeding operation is performed with the center distance between the feed roller and the separating roller fixed.
In that case, it becomes necessary to manually appropriately adjust the center distance in accordance with the original being conveyed, and this adjustment was done in the following procedure.
1. The center distance is set at a position whereat bad separation or the like will not occur to the originals being conveyed.
2. An attempt is made to actually convey several originals.
3. Actual conveyance is effected if conveyance is good.
4. When bad separation or the like occurs, the set value of the center distance is corrected.
5. An attempt is again made to convey several originals.
6. The work mentioned under items 4 and 5 is repetitively done until good conveyance is effected.
This adjustment is requisite in an apparatus having no mechanism for automatically adjusting the center distance, and even in an apparatus having the mechanism for automatically adjusting the center distance, it is necessary to carry out this adjustment whenever the conveyance of originals with the center distance fixed is effected, and much time was required until a set value of the center distance corresponding to the kind of the original was found out.
Also, when the set value was to be found out for an original actually conveyed, the original was stained or damaged in some cases.
So, the present invention has as its object to enable, in the sheet feeding device as described above, or an image reading apparatus or other sheet treating apparatus provided with the sheet feeding device, the setting of an appropriate center distance when a sheet is separated and conveyed with the center distance between the conveying rotary member and the separating rotary member constituting the sheet separating portion to be smoothly effected within a short time.
The present invention provides the following sheet feeding device, sheet treating device and image forming apparatus.
(1) A sheet feeding device which has a sheet separating portion for separating and conveying sheets one by one by a forwardly rotating conveying rotary member and a reversely rotating separating rotary member, center distance changing means capable of relatively changing the center distance between the conveying rotary member and the separating rotary member, control means for controlling the center distance changing means, an operating portion capable of arbitrarily setting the center distance, and a displaying portion for displaying the set value of the center distance set by the operating portion, and has selecting means capable of arbitrarily selecting a first sheet feeding mode for effecting sheet feeding while automatically adjusting the center distance by the center distance changing means and the control means for each sheet, and a second sheet feeding mode in which during the sheet feeding operation, the control means effects sheet feeding with the center distance fixed at the set value displayed on the displaying portion.
(2) The selecting means comprises a first switch capable of arbitrarily selecting the first sheet feeding mode and the second sheet feeding mode, and a second switch for switching the propriety of a center distance setting input for effecting the setting of the center distance when the second sheet feeding mode is selected.
(3) A sheet feeding device according to item (1) or (2), wherein an adjusting input is possible to the set value of the center distance displayed on the displaying portion.
(4) A sheet feeding device according to any one of items (1) to (3), having memory means for storing the set value of the center distance therein, and wherein unless the set value of the center distance is changed, when the second sheet feeding mode is selected, the second sheet feeding mode is executed at the set value of the center distance stored in the memory means.
(5) A sheet treating device having a sheet feeding device according to any one of items (1) to (4), and a treating portion for the sheets fed from the sheet feeding device.
(6) A sheet treating device according to item (5), wherein the treating portion for the sheets is a reading portion, a printing portion, a copying portion, an assorting portion, an applying portion, a heating portion, a cutting portion or a punching portion, or a compound treating portion thereof.
(7) An image reading apparatus having:
a separating portion for separating and conveying sheet-shaped originals one by one by a forwardly rotating conveying rotary member and a reversely rotating separating rotary member;
center distance changing means capable of relatively changing the center distance between the conveying rotary member and the separating rotary member;
control means for controlling the center distance changing means;
adjusting means for adjusting the brightness of a read image;
display means for displaying the adjusted value of the brightness of the read image;
a first switch capable of arbitrarily selecting a first sheet feeding mode for effecting sheet feeding while automatically adjusting the center distance for each original, and a second sheet feeding mode for effecting sheet feeding with the center distance fixed; and
a second switch for switching the propriety of a center distance setting input for effecting the setting of the center distance when the second sheet feeding mode is selected;
wherein when the center distance setting input is made possible by the second switch, the setting of the center distance is effected by the adjusting means for adjusting the brightness of the read image, and the set value of the center distance is displayed by the display means for displaying the brightness of the read image.
(8) An image reading apparatus according to item (7), wherein an adjusting input is possible to the set value of the center distance displayed by the display means.
(9) An image reading apparatus according to item (7) or (8), having memory means for storing the set value of the center distance therein, and wherein unless the set value of the center distance is newly inputted, when the second sheet feeding mode is selected, the second sheet feeding mode is executed at the set value of the center distance stored in the memory means.
That is, when the setting of the center distance during the selection of the second sheet feeding mode for effecting sheet feeding with the center distance between the conveying rotary member and the separating rotary member fixed is to be effected, the center distance setting standard operation (hereinafter referred to as the adjusting operation) of detecting the center distance automatically adjusted when a sheet or any plurality of sheets have been fed in the first sheet feeding mode for effecting sheet feeding with the center distance automatically adjusted for each sheet (original) and displaying the set value of the center distance based on the result of the detection on the display portion is performed, whereby the set value of an appropriate center distance can be easily known by the display portion and thereby, it becomes possible to smoothly effect the setting of the center distance in the case of the second sheet feeding mode for effecting the separation and conveyance of a sheet with the center distance between the conveying rotary member and the separating rotary member of the sheet separating portion fixed within a short time.
Also, the above-described adjusting operation is made executable only when the center distance set value input mode is brought about, whereby the set value of the center distance can be obviated from being inadvertently changed.
By permitting the adjusting input to the set value of the center distance obtained in the adjusting operation, the error of the apparatus is made correctable, and the more reliable separation and conveyance of a sheet in the second sheet feeding mode can be made possible.
Design is made such that the set value of the center distance obtained in the adjusting operation is stored in the memory means and during the selection of the second sheet feeding mode, conveyance is effected in the second sheet feeding mode by the use of this stored set value, whereby when a sheet separated and conveyed in the second sheet feeding mode is of a fixed size, thickness and paper quality, it has become possible to effect the conveyance of the sheet immediately with the adjustment omitted.
In the image reading apparatus, the center distance set value input is used in both the operating portion and the display portion in common with an operating portion and a display portion of other functions, whereby an image reading apparatus which can perform the adjusting operation can be provided without greatly increasing the display portions and operating keys.
Also, by using a center distance setting input key and a set value displaying portion in common with other functions, and yet permitting the adjusting input to the set value of the center distance obtained in the adjusting operation, the error of the apparatus can be made correctable, and an image reading apparatus which can effect the more reliable separation and conveyance of an original in the second sheet feeding mode.
Further, design is made such that the center distance setting input is used in the operating portion and the display portion in common with other functions, and yet the set value of the center distance obtained in the adjusting operation is stored in the memory means and during the selection of the second sheet feeding mode, conveyance is effected in the second sheet feeding mode by the use of this stored set value, whereby there can be provided an image reading apparatus which can effect the conveyance of an original immediately with the adjustment omitted when the original conveyed in the second sheet feeding mode is of a fixed size, thickness and paper quality.